Lenovo G580 does not display on startup and on restart

Hei there, am using a lenovo laptop now its 2 and half years old, it has been working properly but now when i restart it, the power light is on, fun runs and drive also runs but does not display on the screen.
And when i leave it for the whole day it displays but should it shutdown, it does not power back. so i dont know where the problem is. i need your help thanks. it has been doing this for the last 4 months